This invention relates to vehicle braking means and can be used as an emergency, standby or parking brake in any vehicle.
There is known a vehicle braking means comprising a braking mechanism housed in a main chamber to which is attached an auxiliary chamber accommodating a spring-loaded piston and a hollow piston rod adapted to actuate the braking mechanism, there being provided a locking mechanism for the purpose of locking the piston and rod together, the locking mechanism being adapted for connection to a release mechanism.
The auxiliary chamber housing has an external circular flange provided for attachment to the main chamber housing. The braking mechanism comprises a diaphragm gripped between the housings of the main and auxiliary chambers, the two housings being held together by a clamp. The auxiliary chamber housing is closed by a cover having a cylindrical portion coaxial with the housing. Made integral with the cover and coaxially therewith is an internal thin-walled cylinder of a smaller diameter. The end of this cylinder projects outward beyond the housing and cover. The space formed between the cylindrical portion of the cover and the internal cylinder houses a piston spring. The space above the piston is filled with a fluid medium under pressure immediately after mounting the auxiliary chamber on the vehicle. The piston has a hollow endpiece which is made integral therewith and is arranged to fit into the cover interior cylinder so that the piston abuts against the end of the cylinder.
The outward end of the piston endpiece has a threaded sleeve to receive a release bolt the head of which is situated outside the auxiliary chamber housing where it is readily accessible.
The shank of the release bolt passes inside the pistion endpiece and bears against the piston rod located in the auxiliary chamber housing. One end of the piston rod passes through a hole in the end wall of the auxiliary chamber housing, whereas the other end fits through a spacer ring installed in the piston endpiece. Formed in the piston rod end behind the spacer ring is a groove for a locking ring intended to prevent the piston rod from coming out of the piston endpiece. The other end of the piston rod, which extends through a hole in the chamber end wall, mounts a thrust flange. The outward end of the cover interior cylinder carries a protection cap.
A drop of the pressure of the fluid medium in the space above the auxiliary chamber piston, which may result from leaks in the fluid medium supply lines or from an intentional pressure release, causes the piston together with the release bolt and the piston rod to move, by the action of the piston spring, towards the main chamber and to actuate the braking mechanism through the main chamber diaphragm, thereby applying the vehicle brakes.
In order to release the vehicle brakes manually without supplying a fluid medium under pressure into the space above the auxiliary chamber piston, the release bolt is screwed out to permit the reaction of the braking mechanism to move the piston rod. Under these conditions, the release bolt also holds the piston and the piston rod together so that they move bodily during the operation of the auxiliary chamber. The piston rod moves until its thrust flange abuts against the end wall of the chamber housing.
In order to prepare the auxiliary chamber for operation, a fluid medium is supplied under pressure into the space above the piston, whereby the piston is forced into the initial position, compressing its spring. With this condition obtained, the release bolt is screwed in, up to the end of the piston rod.
One of the disadvantages of the construction under consideration is that considerable time is taken to screw out the bolt for releasing the vehicle brakes when there is no pressure of a fluid medium in the auxiliary chamber as well as to screw in the bolt when supplying a fluid medium under pressure to prepare the auxiliary chamber for operation. Further, it is rendered beyond practice to provide a simultaneous remote control of several auxiliary chambers of the known design.